John Chrysostom — as excerpted in the Catena Aurea on Mark 10:35-40

“(ubi sup.) Where two questions are raised, one is, whether a seat on His right hand is prepared for any one; the other, whether the Lord of all has it not in His power to give it to those for whom it is prepared. To the first then we say, that no one sits on His right hand or on His left, for that throne is inaccessible to a creature. How then did He say, To sit on my right hand or on my left is not mine to give you, as though it belonged to some who were to sit there? He however answers the thoughts of those who asked Him, condescending to their meaning; for they did not know that lofty throne and seat, which is on the right hand of the Father, but sought one thing alone, that is, to possess the chief place, and to be set over others. And since they had heard it said of the Apostles, that they were to sit on twelve thrones, they begged for a place higher than all the rest, not knowing what was said. To the second question we must say, that such a gift does not transcend the power of the Son of God, but what is said by Matthew (Matt. 20:23), it is prepared by My Father, is the same as if it were said, “by Me,” wherefore also Mark did not say here, by My Father. What therefore Christ says here is this, Ye shall die, He says, for Me, but this is not enough to enable you to obtain the highest place, for if another person comes possessing besides martyrdom all other virtues, he will possess much more than you; for the chief place is prepared for those, who by works are enabled to become the first. Thus then the Lord instructed them not to trouble themselves vainly and absurdly for high places; at the same time He would not have them made sad.”